Bring 6 quarts of salted water to a boil in an 8-quart pot over high heat.,Heat 2 tablespoons of the olive oil in a large skillet over medium heat.,Add the pancetta and cook, stirring occasionally, until the pancetta has rendered some of its fat and is lightly browned but still soft in the center, about 4 minutes.,Don't overcook the pancetta.,Stir the cavatelli into the boiling water.,Return to a boil, stirring frequently.,Cook the pasta, semi-covered, stirring occasionally, until done, about 10 minutes.,Stir the onions into the skillet and cook until barely wilted, about 2 minutes.,Stir in the cauliflower and cook, stirring occasionally, until the cauliflower is wilted and begins to brown, about 4 minutes.,______,Pour the chicken stock into the skillet, bring to a boil, and lower the heat so the sauce is at a lively simmer.,Cook until the vegetables are tender and the liquid is reduced by about one-half, about 5 minutes.,If the skillet is large enough to accommodate the sauce and pasta, fish the pasta out of the boiling water with a large wire skimmer and drop it directly into the sauce in the skillet.,If not, drain the pasta, return it to the pot, and pour in the sauce.,Bring the sauce and pasta to a boil, tossing and stirring to coat the pasta.,Check the seasoning, adding salt if necessary.,Stir the bread crumbs, parsley, and remaining 2 tablespoons olive oil in the pot.,Cook, stirring and tossing the pasta, until the sauce is lightly thickened.,Serve at once & enjoy!